Se fugó translates to "ran away" or "escaped." While it can literally mean to flee, in this song, it's used metaphorically to describe the sudden and unexpected disappearance of love.
The lyrics state, "O sea que nuestro amor se fugó" (Meaning our love ran away). This phrase personifies love, giving it the ability to escape, which adds a dramatic and poignant touch to the heartbreak expressed in the song. It's a more evocative way to say love ended than simply saying it disappeared.
CNCO built «Qué Va A Ser De Mí» around one repeated fear: a partner is about to walk out, and the singer keeps asking «¿Qué va a ser de mí?» (“What will become of me?”) every time the thought crosses his mind. He measures the loss in physical terms rather than abstractions — «Sin tu calor, sin tu olor» (“Without your heat, without your smell”) — and pushes the stakes as high as they go: «Si yo no tengo de tu amor, me moriré» (“If I don’t have your love, I will die”).
By the bridge the pleading turns into a confession. He stops asking her to stay and starts asking what he did wrong: «Dime, si el culpable fui yo» (“Tell me, if I was the culprit”). The song never answers its own question — it just circles back to the hook one more time, which is the point.